Signal processing systems may be implemented using a variety of integrated circuits controlled by one or more control microcomputers (.mu.C). Communications between the various functions typically involves a data bus such as a serial data bus. To incorporate all desired functions in a bus-controlled signal processing system, it may be necessary to utilize signal processing integrated circuits (IC) from various manufacturers. However, manufacturers support several different communications protocols. For example, Philips and ITT support bus standards designated the Inter IC (IIC or I2C), and Intermetall (IM) standards, respectively.
Use of multiple communications protocols on a single data bus introduces the possibility that an integrated circuit (IC) dedicated to one protocol will misinterpret signals formatted under a different protocol. Bus standards specify signal patterns that indicate message start and end conditions, device address, and message data for devices coupled to the bus. For example, a particular transition occurring on one signal during a particular state on another signal indicates "start of message" for the IIC bus standard. Signal waveforms that are generated to conform to IM bus standard may inadvertently create the "start message" condition for the IIC bus. If both IM and IIC devices are connected to a bus, an IIC device may be activated unintentionally during an IM format message. As a result, two devices attempt to communicate simultaneously on the bus. Corruption of any transmission that is in progress and incorrect system operation may result.
The occurrence of the described bus conflicts will depend on data values and timing. Thus, the conflicts and any subsequent system malfunctions will be intermittent. Testing of the system may identify data patterns that should be avoided to prevent bus conflicts. However, exhaustive and lengthy testing of all possible data patterns may be required to ensure reliable system performance. In addition, it would be necessary to repeat the testing when a device type is changed or a new device is added to the bus.